An optical detection system, such as a system for providing light detection and ranging (LIDAR), generally includes a light source (e.g., an illuminator) and an optical receiver. Various schemes can be used to provide illumination of a field-of-regard, such as a flash technique in which a large portion or an entirety of the of the field-of-regard is illuminated contemporaneously. In another approach, scanning can be used to selectively illuminate portions of the field-of-regard. Such scanning can include use of one or more mechanical actuators such as rotating or oscillating mirrors or prism structures to orient a beam of light toward specified portions of the field-of-regard. In yet another approach, a non-mechanical beam-steering technique can be used, either alone or in combination with a mechanically-scanned technique. Optical detection systems such as LIDAR can be applied in vehicular applications, such as to facilitate operation of autonomous vehicles. Other applications can include beam guidance to facilitate communication or tracking of an object, for example.